package com.thealgorithms.searches;

import com.thealgorithms.devutils.searches.MatrixSearchAlgorithm;

/**
 * The search is for any array which is sorted row and column-wise too. For ex :
 * {{10, 20, 30, 40},
 *  {15, 25, 35, 45},
 *  {18, 28, 38, 48},
 *  {21, 31, 41, 51}}
 *
 * This array is sorted in both row and column manner.
 * In this two pointers are taken, the first points to the 0th row and the second one points to end column, and then the
 * element corresponding to the pointers placed in the array is compared with the target that either its equal, greater or
 * smaller than the target. If the element is equal to the target, the co-ordinates of that element is returned i.e. an
 * array of the two pointers will be returned, else if the target is greater than corresponding element then the pointer
 * pointing to the 0th row will be incremented by 1, else if the target is lesser than the corresponding element then the
 * pointer pointing to the end column will be decremented by 1. And if the element doesn't exist in the array, an array
 * {-1, -1} will be returned.
 */
public class RowColumnWiseSorted2dArrayBinarySearch
  implements MatrixSearchAlgorithm {

  @Override
  public <T extends Comparable<T>> int[] find(T[][] matrix, T key) {
    return search(matrix, key);
  }

  public static <T extends Comparable<T>> int[] search(T[][] matrix, T target) {
    int rowPointer = 0; //The pointer at 0th row
    int colPointer = matrix.length - 1; //The pointer at end column

    while (rowPointer < matrix.length && colPointer >= 0) {
      int comp = target.compareTo(matrix[rowPointer][colPointer]);

      if (comp == 0) {
        return new int[] { rowPointer, colPointer };
      } else if (comp > 0) {
        rowPointer++; //Incrementing the row pointer if the target is greater
      } else {
        colPointer--; //Decrementing the column pointer if the target is lesser
      }
    }
    return new int[] { -1, -1 }; //The not found condition
  }
}
